Carboxylated diphenylether-formaldehyde copolymer resins and their preparation

Abstract

Novel copolymer resins having the repeating unit ##STR1## WHEREIN EACH R is independently alkyl of 1 to about 10 carbon atoms or halogen, z is oxygen or sulfur, the dashed line is an optional chemical bond, the group represented by z taken with the dashed line represents dibenzofuran and dibenzothiophene moieties, or mixtures thereof, each R" is hydrogen or ##STR2## wherein each R' is a hydrocarbon or substituted hydrocarbon radical of from 2 to about 11 carbon atoms, n averages about 3-10, each m is 0-2 and p and q are each 0 or 1 with the proviso that the sum of p and q has an average value of 0.1-1.0 and there is an average of at least one carboxyl group per polymer molecule, are prepared by reacting a mixture comprising a hydroxymethylated diphenylether-formaldehyde copolymer with an anhydride of the formula ##STR3## wherein R' is a hydrocarbon or substituted hydrocarbon radical of from 2 to about 11 carbon atoms, at a temperature between about 120° and about 170° C. The copolymer resins form stable aqueous solutions in the presence of base which, when heated in the presence of a water-soluble curing agent, such as hexamethoxymethylmelamine, yield glossy, flexible and impact-, solvent-, and water-resistant films.

What is claimed is: 
     
       1. A copolymer resin having the repeating unit ##STR9## wherein each R is independently an alkyl group of 1 to about 10 carbon atoms or a halogen, z is oxygen or sulfur, the dashed line is an optional chemical bond, the group represented by z taken with the dashed line represents dibenzofuran and dibenzothiophene moieties, or mixtures thereof, each R" is hydrogen or ##STR10## wherein each R' is a substituted or unsubstituted alkylene or arylene radical of 2 to about 11 carbon atoms, n averages about 3-10, each m is 0-2, and p and q are each 0 or 1 with the proviso that the sum of p and q has an average value of 0.1-1 and there is an average of at least one carboxyl group per polymer molecule. 
     
     
       2. The copolymer resin of claim 1 wherein z is oxygen. 
     
     
       3. The copolymer resin of claim 2 wherein the dashed line is absent. 
     
     
       4. The copolymer resin of claim 3 wherein each R is a branched, lower alkyl. 
     
     
       5. The copolymer resin of claim 3 wherein each m is 0. 
     
     
       6. The copolymer resin of claim 5 wherein R' is ethylene. 
     
     
       7. The copolymer resin of claim 5 wherein R' is o-phenylene. 
     
     
       8. The copolymer resin of claim 1 which includes a curing amount of a curing agent. 
     
     
       9. The copolymer resin of claim 8 in a cured state. 
     
     
       10. A process for preparing the copolymer resin having the repeating unit of claim 1 comprising heating with agitation a mixture comprising a. a hydroxymethyl substituted diphenylether-formaldehyde copolymer resin having the repeating unit ##STR11##  wherein each R is independently alkyl of 1 to about 10 carbon atoms or halogen, z is oxygen or sulfur, the dashed line is an optional chemical bond, the group represented by z taken with the dashed line represents dibenzofuran and dibenzothiophene moieties, or mixtures thereof, n averages about 3-10, m is 0-2, and p and q are each 0 or 1 with the proviso that the sum of p and q has the average value of 0.1-1 and there is an average of at least one hydroxymethyl group per polymer molecule, and   b. an anhydride of the formula ##STR12##  wherein R' is a substituted or unsubstituted alkylene or arylene radical of from 2 to about 11 carbon atoms, to a temperature between about 120° C and about 170° C for about 10 to about 50 minutes wherein the ratio of (b) to (a) is between about 0.1 to about 1.1 mole of (b) per equivalent hydroxyl group in (a).     
     
     
       11. The process of claim 10 wherein the mixture is heated to a temperature between about 140° and about 160° C for about 20 to 40 minutes. 
     
     
       12. The process of claim 10 wherein the ratio of (b) to (a) is about 1 mole of (b) per equivalent of hydroxy group in (a). 
     
     
       13. The process of claim 10 wherein the mixture is heated in an extrusion zone.